Multi-mode controller

ABSTRACT

A method and system for wireless communication is provided and may include, scanning by a wireless communication device, a plurality of radio frequencies for beacon messages from a plurality of master communication devices, in order to identify whether establishment of communication with at least one of said plurality of time-synchronous RF networks is possible. Each of the plurality of master communication devices may be associated with one of a plurality of time-synchronous RF networks. A network associated with one of the beacon messages may be selected based on predefined criteria. The selected network may be one of the plurality of time-synchronous RF networks. Communication may be established with said selected network by the wireless communication device. The plurality of time-synchronous RF networks may comprise a Bluetooth network and/or IEEE 802.11 Wireless Local Area (WLAN) network.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.09/866,546 filed May 25, 2001 now U.S. Pat. No. 7,114,010, which in turnmakes reference to, claims priority to and claims the benefit of: U.S.Provisional Patent Application Ser. No. 60/214,620 filed on Jun. 28,2000 and U.S. Provisional Patent Application Ser. No. 60/238,833 filedon Oct. 6, 2000.

FIELD OF THE INVENTION

The invention relates generally to data communications and, moreparticularly, to systems and methods for controlling and managingnetwork access in wireless communication systems.

BACKGROUND OF THE INVENTION

Demand for wireless information services had led to the development ofan ever increasing number of wireless network standards. For example,cellular and PCS networks, to name just two, provide wide area wirelesstelephone and data services. As the demand for these services increases,portable communication devices such as personal digital assistants(PDAs) are evolving to support integrated voice, data, and streamingmedia while providing seamless network coverage from personal areanetworks (PAN) to wide area networks (WAN). On the wireless WAN side,the prevailing standards are 2G+, 3G and 4G, among others. On thewireless PAN and local area networks (LAN) side, Bluetooth, HomeRF, andIEEE 802.11b standards are emerging as important standards. A Bluetoothnetwork may provide data connectivity between devices such as personalcomputer and personal digital assistants (PDAs) that are in relativelyclose proximity to one another. A HomeRF network may provide wirelessservices at relatively high data rates over a small area of coveragesuch as a person's home.

Boundaries between wireless WANs (including cellular networks) and LANs(e.g., home wireless LANs and other small pockets of wireless networks)are essentially disappearing as customers demand seamless continuationof service for their mobile communication device as they travel fromtheir PAN to home network and further into the WANs.

However, in general, devices that are compatible with one wirelessnetwork are incompatible with other wireless networks. This is due, inpart, to each network's use of its own unique set of protocols forfacilitating communication between compatible devices.

Moreover, each network typically provides a unique set of services.Networks may provide different data transmission rates, for example, aGSM cellular telephone network typically supports data transfer rates of64 kilobits per second (kbit/s) while a HomeRF network may support datatransfer rates of 2-10 megabits per second. Networks also may provideservice having different areas of coverage. For example, cellularnetworks provide coverage on a continental scale while Bluetoothnetworks typically provide coverage over the range of approximately 10meters. Networks also may provide different information content to auser of the network. Legacy cellular telephone networks simply providedvoice services. Newer networks such as PCS networks may support voice,data and other information services.

In effect, these disparate networks have created a series of islands ofwireless service throughout the geographical landscape, each with itsown unique set of protocol standards, data rates, areas of coverage andservices. Yet there are no single wireless technologies or standardsthat effectively satisfy the requirements of desired coverage area (fromPAN to WAN) and quality of service (high bandwidth data, voice, andstreaming media) for mobile multimedia devices.

SUMMARY OF THE INVENTION

The invention is directed to systems and methods for enabling a wirelesscommunication device to communicate with a variety of wireless networks.In particular, a portable communication device constructed according tothe invention can communicate with different networks as the device ismoved through the areas of coverage supported by the different networks.To this end the invention provides techniques for controlling andmanaging network access to several networks. As a result, a deviceconstructed according to the invention can take advantage of servicesprovides by a particular network when the device is within the area ofcoverage provided by that network. For example, when the device iswithin the area of coverage of a network that provides high speedInternet access, the device may switch from the network with which itwas connected to the network with the high speed Internet access.Similarly, the device may, for example, connect to networks that providedifferent quality of service, low cost service and/or different services(e.g., voice, data, multimedia, etc.).

In one embodiment, the invention relates to systems and methods forimplementing multi-mode wireless communication devices such as PDAs ormulti-function (e.g. data, voice, and multimedia) mobile phones thatbest take advantage of the wireless networks in their proximity. Thatis, in the case where a nearby wireless network (WAN, LAN, or PAN)happens to provide more data bandwidth and/or better quality of service(QoS), a multi-mode wireless device may switch to that particularwireless network to access these services. Several network coveragescenarios include, for example:

-   (1) a PDA or a multi-function mobile phone connected to a low    bandwidth internet service while located within a WAN could take    advantage of a broadband internet service while located at home    through a wireless LAN;-   (2) a cellular phone could switch to a cordless telephone mode when    at home to make calls over the wired infrastructure to avoid    air-time charges;-   (3) a PDA or a multi-function cell phone traveling through a WAN may    encounter an island of high bandwidth wireless coverage (Bluetooth,    HomeRF, 802.11b, etc.) in which case it could switch to a Bluetooth,    HomeRF, or 802.11b mode to access the provided services;-   (4) A Bluetooth enabled mobile WAN device may recognize and    establish connection with a nearby HomeRF network; and-   (5) A Bluetooth enabled mobile WAN device WAN device may recognize    and establish connection with a nearby IEEE 802.11b network.

One embodiment of a system constructed according to the inventionconsists of a multi-mode controller that, in effect, simultaneouslyprocesses communication signals for several wireless networks. Themulti-mode controller processes signals to detect the presence ofnetwork services and, in the event services are detected, selectivelyestablishes communications between the device and the network.

One embodiment of a system constructed according to the inventionconsists of a dual-mode Bluetooth and HomeRF controller. The dual-modecontroller, in effect, simultaneously generates polling signals andscans for polling signals to detect the presence of Bluetooth and HomeRFnetwork services. In the event such services are detected, the deviceselectively establishes communications between the device and one of thetwo networks.

One embodiment of a system constructed according to the inventionconsists of a dual-mode Bluetooth and IEEE 802.11b controller. Thedual-mode controller, in effect, simultaneously generates pollingsignals and scans for polling signals to detect the presence ofBluetooth and IEEE 802.11b network services. In the event such servicesare detected, the device selectively establishes communications betweenthe device and one of the two networks.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention will be more fully understood when considered with respect tothe following detailed description, appended claims and accompanyingdrawings, wherein:

FIG. 1 is a graphical representation of one embodiment of wirelesscommunication networks defining different areas of coverage wherein adevice constructed according to the invention may establishcommunication with one or more of the wireless communication networks;

FIG. 2 is a block diagram of one embodiment of a multi-mode radiotransmitter/receiver constructed in accordance with the invention;

FIG. 3 is a block diagram of one embodiment of a multi-mode radiotransmitter/receiver constructed in accordance with the invention;

FIG. 4 is a block diagram of one embodiment of a multi-mode controllerand user interface in accordance with the invention;

FIG. 5 is a graphical representation of one embodiment of acommunications system including Bluetooth and HomeRF networks wherein adevice constructed according to the invention may establishcommunication with the Bluetooth and HomeRF networks;

FIG. 6 is a block diagram of one embodiment of a dual mode Bluetooth andHomeRF radio transmitter/receiver constructed in accordance with theinvention;

FIG. 7 is a graphical representation of a Bluetooth network accessprocedure;

FIG. 8 is a graphical representation of a HomeRF network accessprocedure;

FIG. 9 is a graphical representation of one embodiment of a dual-modeBluetooth and HomeRF network access procedure in accordance with theinvention;

FIG. 10 is a flowchart representative of one embodiment of a Bluetoothand HomeRF dual-mode controller state transition diagram in accordancewith the invention;

FIG. 11 is a block diagram of one embodiment of a dual mode Bluetoothand IEEE 802.11b radio transmitter/receiver constructed in accordancewith the invention;

FIG. 12 is a graphical representation of a IEEE 802.11b network accessprocedure;

FIG. 13 is a graphical representation of one embodiment of a dual-modeBluetooth and IEEE 802.11b network access procedure in accordance withthe invention; and

FIG. 14 is a flowchart representative of one embodiment of a Bluetoothand IEEE 802.11b dual-mode controller state transition diagram inaccordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described below, with reference to detailedillustrative embodiments. It will be apparent that the invention can beembodied in a wide variety of forms, some of which may be quitedifferent from those of the disclosed embodiments. Consequently, thespecific structural and functional details disclosed herein are merelyrepresentative and do not limit the scope of the invention.

FIG. 1 is a simplified graphical representation of a communicationssystem S defined by several wireless networks. Dashed lines 20, 22 and24 represent hypothetical areas of coverage for a few representativewireless networks. In this embodiment, wireless communication device 26is associated with one network (designated network 1) and its associatedarea of coverage 20. Similarly, wireless communication devices 28 and 32are associated with another type of network (designated network 2) whereeach wireless communication device 28 and 32 is associated with adistinct area of coverage 22 and 24, respectively.

In accordance with one embodiment of the invention, multi-modecommunication devices 30 and 34 may communicate with one or more of thewireless communication devices 26, 28 and 32. Essentially, eachmulti-mode communication device 30 or 34 determines whether it is withinthe area of coverage of a type of network that is supported by themulti-mode communication device. For example, as multi-modecommunication device 30 moves from a location outside of area 22 to alocation within area 22, the device 30 may selectively establishcommunications with a device in the wireless network represent by area22 (e.g., device 28).

Depending on the location of a multi-mode communication device 30 or 34,the device 30 or 34 may be in an area of coverage for zero, one, two ormore networks. Hence, in some situations the device 30 or 34 may need toselect a network to which it will connect. As will be discussed indetail below, the decision to connect to a network may be based ondifferent factors including, for example, the data transfer ratesprovided by the networks.

Typically, the devices depicted in FIG. 1 and discussions in thesections that follow are portable devices. However, it should beunderstood that the teachings of the invention may be applied tostationary devices in some applications.

FIG. 2 is a simplified block diagram illustrating certain components ofa multi-mode communication device that may operate with two or morewireless networks. A multi-mode controller 40 controls and managesnetwork access to the wireless networks for the communication device.Processing elements 42 and 44 perform the signal processing associatedwith a given network. As represented by ellipses 52, any number ofprocessing elements for any number of networks may be supported,consistent with the teachings of the invention. Thus, the designation“N” for processing element 44 may represent the Nth network supported bythe communication device.

The multi-mode controller 40 and the processing elements 42 and 44communicate with the network via a radio interface 46. The radiointerface transmits and receives signals (e.g., radio frequency signalssuch as microwave signals and those in the cellular and PCS bands) toother devices in a network via an antenna 48.

A user interface 50 enables a user (not shown) to transmit and receiveinformation to and from a selected network via the correspondingprocessing elements 42 or 44 and the radio interface 46.

FIG. 3 is a block diagram that represents network selection operationsthat may be performed in accordance with the invention. In someinstances, a multi-mode communication device will select one of two ormore available networks. To this end, the device may selectively routeinformation to/from a user interface 66 from/to another device in theselected network. Thus, information will be routed to/from anappropriate network processor element 60 or 62. This selection may bebased on many factors. The device may select a network with, forexample, 1) a higher bandwidth; 2) a broader area of coverage; 3) lessexpensive connection costs; 4) different QoS; or 5) better services(e.g., Internet access, multi-media access, etc.).

In one embodiment, a network selector 64 may consist of a hard switch(e.g., a multiplexor) that routes signals from one component to another.In another embodiment the functions of the network selector 64 may beaccomplished using routing software that routes the information to anappropriate hardware component or a software subroutine. In the lattercase, the network processing operations may take the form of softwareroutines, whereby the multi-mode controller may control execution of theappropriate routine for the selected network. In this case, theinformation would then be routed to the enabled routine. Such anembodiment typically would be used in an implementation where themulti-mode controller and network processing functionality is performedby a common processing element such as a digital signal processor.

FIG. 3 also illustrates that in some embodiments different radiointerfaces 68 and 70 may be use for interfacing with different networks.Also, several antennae may be used in some applications.

FIG. 4 further illustrates operations related to selecting a network. Amulti-mode controller 80 receives network information 88 indicative ofwhether the device is within range of a supported network. An activenetwork detector 92 processes the received network information todetermine whether the device is within range of a supported network. Insome embodiments, network detection involves sequentially sending and/orscanning for network polling information associated with each network.

A network selector 94 may be used to determine whether to connect to adetected network. In some instances the device may be configured to onlyconnect to certain types of networks. In other instances the device maybe configured to choose between two or more detected networks.

In practice, the decision to select a particular network may be based ona variety of factors. A given network may provide better quality ofservice than another network. One network may provide faster rates ofdata transfer. One network may provide less congestion. A network may beless expensive to use. A network may provide content (e.g., Internetaccess) that another network does not provide. One network may provideinformation services (e.g., voice, data, multimedia) that are notprovided by another network.

Many different schemes may be used to connect to a given network. Forexample, a device constructed according to the invention may query theuser so that the user can decide whether to connect to a particularnetwork. For example, the multi-mode controller may send a message thatis displayed on a display 98 in the user interface 82. The user may thenuse an input device 100 to send instructions to the multi-modecontroller 80 regarding the user's selection.

Alternatively, a device constructed according to the invention mayautomatically connect to a network. In the embodiment of FIG. 4, a datamemory 84 may include information 96 that indicates, for example, thatthe device should: 1) never connect to a particular network; 2) alwaysconnect to a particular network if that network is detected; 3) promptthe user of the device for input as to whether the user wishes toconnect to the network; and/or 4) connect to the network depending onother options. Examples of options in the last category (number four)include a switch on the device indicative of the user's preference undercertain conditions or comparison of the service (e.g., availablebandwidth, quality of service, networks costs) available from eachnetwork.

Once a network has been selected, a connection manager 102 establishescommunication with the network by, for example, causing the appropriatenetwork processor 60 or 62 (FIG. 3) to send the necessary signals toanother device in the network (as represented by block 90).

One embodiment of the invention relates to a method for a multi-modewireless communication device to access and take advantage of theproximity wireless network that best satisfies its service needs. Inparticular, this embodiment includes a dual-mode wireless network chipset architecture that combines wireless PAN and LAN functions. Thedual-mode operation is achieved by a device called a dual-modecontroller (DMC) which controls and manages network access to a nearbyPAN or a LAN.

FIG. 5 depicts one embodiment of the invention that enables a device toutilize Bluetooth and HomeRF networks. Central to this embodiment is aBluetooth and HomeRF dual mode controller as discussed in more below.

A Bluetooth network is categorized as a personal area network (PAN).PANs such as Bluetooth typically have a range on the order of tenmeters. Conventionally, Bluetooth devices support data transfer rates inthe range of 1 Mbit/s. Current Bluetooth specifications includeBluetooth versions 1.0 and 1.1.

In some instances, Bluetooth networks may be used in ad hoc peer-to-peercommunications. Examples of communications over a Bluetooth network mayinclude data transfers between a PDA and a nearby laptop computer orbetween a digital camera and a personal computer. In addition, an MP3player may communicate with a computer or “juke box” over a Bluetoothnetwork.

A HomeRF network is categorized as a local area network (LAN) and, assuch, typically supports communications over a area of coverage ofapproximately 100 meters. Conventional HomeRF devices support datatransfer rates on the order of two to ten Mbit/s. Current HomeRFspecifications include the Shared Wireless Access ProtocolSpecification, versions 1.3 and 2.0.

Typically, a wireless PAN connects to a backbone that provides dataconnectivity to other networks. For example, a wireless PAN interfacemay connect to a T1 line to provide Internet connectivity. Alternativelya cable modem may include a wireless PAN interface that provides LANconnectivity to wireless devices that are within close proximity to thecable modem.

Significantly, both Bluetooth and HomeRF incorporate frequency hopping.Thus, in this embodiment of the invention a portion of the RF front endmay be effectively shared by the two networks. That is, some of the samecircuits in the RF front end are used when the device is communicatingwith other Bluetooth devices or with other HomeRF devices.

Referring now to FIG. 5, for purposes of explanation, an embodiment of adual-mode mobile communication device 110 capable of accessing eitherBluetooth network devices 112 or HomeRF network devices 116 will bedescribed in the context of a residential gateway (e.g. a cable modemwith a HomeRF wireless LAN interface 120). The residential gateway mayprovide a multi-user broadband internet access service and multi-channelcordless telephony via HomeRF interface. A PDA or a mobile phone with adual-mode Bluetooth-HomeRF capability could switch to a HomeRF mode uponentering a home to take advantage of the broadband internet accessservice, or multi-channel cordless telephony service to avoid airtimecharges while making a call.

In FIG. 6, a chip architecture that provides this dual-modefunctionality is illustrated. A dual-mode radio front-end 132 can beshared with different frequency hopping and modulation rate parametersbetween Bluetooth and HomeRF modes of operation. To achieve a dual-modeoperation, a new timing mechanism (and respective state machines) isused since both Bluetooth and HomeRF are time-synchronous networks. Adual-mode controller 130 implements this timing mechanism and the statemachines to achieve the dual-mode operation.

The dual-mode controller 130 has the following operational modes:

-   -   Bluetooth-only mode    -   HomeRF-only mode    -   Dual Bluetooth-HomeRF mode

In this embodiment, all three modes are set by an external user command.In the Bluetooth-only or HomeRF-only mode, the device operates in thenative Bluetooth or HomeRF mode, respectively, i.e., whichever mode thedevice is in the other mode would be turned off. In the dualBluetooth-HomeRF mode, Bluetooth and HomeRF baseband processors 134 and136, respectively, time-share the dual-mode radio front-end 132 underthe time-synchronous management of the dual-mode controller 130.

The role of the dual-mode controller 130 may be better understood byfirst explaining the native Bluetooth and HomeRF network accessmechanisms. FIG. 7 illustrates what is called “inquiry scan procedure”used by new Bluetooth devices to access a nearby Bluetooth network. ABluetooth master device (by default the first device that formed aBluetooth network) sends a train of special inquiry sequences to probeif there are any new Bluetooth devices in the vicinity. The specialinquiry sequences denoted by “A” and “B” each contain 8 frames whereeach frame is of time duration 1.25 ms and consists of a master-to-slavetransmission slot (0.625 msec) and a slave-to-master transmission slot(0.625 msec). In every master-to-slave transmission slot, the mastersends an inquiry access code on two consecutive hopping frequencies,thereby, covering 16 hopping frequencies for every 8 frames that make upthe inquiry sequence “A.” As shown in FIG. 7, the inquiry sequence “A”is repeated 256 times. There are a total of 32 predetermined hoppingfrequencies allocated to the inquiry procedure. In the event that noinquiry response is received by the master during the first 2.56 secinterval, the remaining set of 16 hopping frequencies are used intransmitting another train of inquiry sequences denoted by “B” as shownin FIG. 7.

New devices entering a Bluetooth network scan for inquiry sequencestransmitted by a master device. The inquiry scan mechanism is also shownin FIG. 7. A new device scans the RF spectrum at a single hoppingfrequency for 11.25 ms in every 2.56 seconds interval. For each newscanning window, a new hopping frequency is selected based on apredetermined frequency hopping sequence. Upon receiving a valid inquirycode sequence, the new unit picks a random number N<64 and continues tosearch for inquiry messages on the same hopping frequency. The unit thentransmits an inquiry response message (containing the unit's access IDand other parameters) in the Nth slave-to-master slot corresponding tothe master-to-slave slot that carried a valid inquiry code. Sending aninquiry response message at a randomly chosen slave-to-master slotreduces the probability of collision for transmissions by multiple newunits responding to the same inquiry access code. The bound on therandom number N is chosen such that the inquiry response message is sentto the master unit within the same train of inquiry code sequences “A”or “B”. Once the master unit receives an inquiry response message, theactual connection set up procedure is performed.

FIG. 8 describes the HomeRF network scan procedure for a new isochronousdevice (called I-node) to join a HomeRF network managed by a ControlPoint (CP). In this case, the CP transmits a distinctive TDMA beaconevery 20 msec at the beginning of each superframe. The superframeduration (20 msec) is based on the frequency hopping rate (50 hops/sec),i.e., each superframe is sent at a different hopping frequency. Thebeacon contains specific information about joining the HomeRF network. Anew I-node performs a network scan procedure to search for a CP beaconon one of the three predetermined network scan frequencies for 1.52seconds.

Unless a beacon is received, all three scan frequencies are tried (eachfor 1.52 sec) in search of a CP beacon. If a TDMA beacon is receivedwithin the scanning window, the new I-node then extracts the networkidentity information and the timing information from the beacon to jointhe HomeRF network.

HomeRF network access mechanism for a new device is somewhat similar tothe Bluetooth network access mechanism. In both cases, the new deviceseeking admission into the network starts a network scan proceduresearching for a special message from a master unit (for a HomeRFnetwork, the master is the CP). This similarity establishes the basisfor the operation of the dual-mode controller device. For a dual-modeBluetooth-HomeRF communication device, the dual-mode controller managesthe network access mechanism for both Bluetooth and HomeRF networks in asynchronous manner. A general illustration of the time interleavedaccess procedure is shown in FIG. 9.

The dual-mode controller (DMC) device includes a new synchronous statemachine that combines the standby, inquiry scan, network scan, andconnection procedures carried out by Bluetooth and HomeRF devices. Thedual-mode Bluetooth-HomeRF devices interoperate with standards based onBluetooth-only or HomeRF-only devices. Network scan and connection setupprocedures for a dual-mode device should follow the same rules asspecified in the Bluetooth or HomeRF standards. In other words,dual-mode operation of the described embodiment should not alter thesynchronous time flow of interdependent states (idle, network scan, scanresponse, etc.) that accomplish the respective network access proceduresfor Bluetooth or HomeRF networks. The exemplary dual-mode controller isconfigured such that Bluetooth and HomeRF network access state machinesare combined without individually altering their functionalities.Detailed description of the dual-mode controller state machine isillustrated in FIG. 10.

The default state for the dual-mode controller is the standby mode. Inthe absence of any network connection, the dual-mode controllerinitiates a new network scan request every 10.24 seconds. The very firstnetwork scan performed by the dual-mode controller searches for a HomeRFnetwork. In this state, a new device performs a network scan procedureon one of the three HomeRF network scan frequencies for 1.52 secsearching for a CP beacon. Unless a beacon is received, all three scanfrequencies are tried (each for 1.52 sec) in search of a CP beacon asshown in FIG. 9. Total duration of the HomeRF network scan procedure is10.24 seconds. If a TDMA beacon is received within the scanning window,the new unit extracts the network identity information and the timinginformation from the beacon to join the HomeRF network. However, beforethe new device attempts to join the HomeRF network based on the beaconinformation, the user is informed via a display message etc. about theexistence of a HomeRF network and the types of services that areavailable. Accordingly, the user may either approve or disapprovejoining the HomeRF network for the specified services. If the userdirects the dual-mode controller to establish a connection with theHomeRF network, the dual-mode device then joins the HomeRF network andmaintains connection until the device transitions into an idle mode oruntil the CP beacon is no longer received by the unit. In both cases,the dual mode device goes into the dual-mode standby mode. If the userdoes not approve connecting to a HomeRF network, the dual-modecontroller automatically starts an inquiry scan procedure to search forthe existence of a Bluetooth network 188. As illustrated in FIG. 10, thedual-mode controller jumps to the same state, that is, starting aBluetooth inquiry scan if the initial HomeRF network scan fails to finda CP beacon. In this case, the Bluetooth inquiry scan procedure is alsorun for 10.24 seconds. This time duration is divided into four inquiryscan periods of each 2.56 seconds. As shown in FIG. 9, the inquiry scanprocedure involves searching for a valid inquiry code for 11.25 msec(covering 16 inquiry frequencies) in a 2.56 second interval at a singlehop frequency. The same procedure is repeated at different hopfrequencies until an inquiry code is received, but no more than 3 times.If a valid Bluetooth inquiry code is not received within the 10.24second interval, the dual-mode device goes back to the dual-mode standbymode 170. In case the unit receives a valid inquiry code 190, it goesinto an inquiry-response mode 192 followed by the connection set upprocedure 194 with the master as described earlier in the text. Finally,if there is no more data to be sent, the Bluetooth connection isterminated 196, and the dual-mode device goes back into the dual-modestandby mode 170.

The embodiment described above typically would be implemented in one ormore integrated circuits. For example the section including the basebandprocessors, 134 and 136, the central processing unit 142 and the hostinterfaces 138 and 140 may be implemented in a single CMOS integratedcircuit and the RF section may be implemented in a single integratedcircuit. It should be appreciated, however, that the teachings of theinvention may be implemented using a wide variety of electroniccomponents and, typically, software programs.

As in the embodiments of FIGS. 2-5, the operations of the dual modecontroller may be implemented using various combinations of hardware andsoftware. Hence, operations of the state machine of FIG. 10 may beimplemented using software code running on a processor or ashardware-based logic. For example, a network scanner component orrouting may be used for the network scan operations. A connectionmanager component or routine may be used for the connection procedure.Note that these two operations may correspond with the network detector92 and the connection manager 102 of FIG. 4.

In addition, a dual-mode communication device incorporating thisembodiment may include various optional user interfaces such as an audiointerface and a visual interface for textual, graphical and videopresentations. The device also includes an interface for user input(e.g., a keypad). The host interface may interface to a broadbandbackbone including, for example, an ethernet connection, satelliteconnection, wireless broadband, cable or the public switched telephonenetwork (PSTN). Typical implementations of such a device may include,for example, PDAs, cellular telephones, MP3 players, still and videocameras and video recorders.

FIG. 11 depicts one embodiment of the invention consisting of adual-mode mobile communication device that is capable of accessingeither a Bluetooth or a Point-Controller (PC) controlled IEEE 802.11bnetwork. 802.11b networks fall under the category of a local areanetwork (LAN). Conventional 802.11b devices support data transfer rateson the order of 5.5 Mbits/s and 11 Mbit/s.

This embodiment is described in the context of a residential gateway(e.g. a cable modem with an 802.11b wireless LAN interface) providing amulti-user broadband internet access service and multi-channel cordlesstelephony via an 802.11b interface. A PDA or a mobile phone with adual-mode Bluetooth-802.11b capability could switch to an 802.11b modeupon entering a home to take advantage of the broadband internet accessservice, or multi-channel cordless telephony service to avoid air-timecharges while making a call.

In FIG. 11, a chip architecture that provides this dual-modefunctionality is illustrated. A dual-mode radio front-end 202 can beshared with different RF front-end and modulation rate parametersbetween Bluetooth and 802.11b modes of operation. To achieve a dual-modeoperation, a new timing mechanism (and respective state machines) isrequired since both Bluetooth and 802.11b systems are time-synchronousnetworks. A dual-mode controller 200 as shown in FIG. 11 implements thistiming mechanism and the state machines to achieve the dual-modeoperation.

The dual-mode controller 200 has the following operational modes:

-   -   Bluetooth-only mode    -   802.11b-only mode    -   Dual Bluetooth-802.11b mode

In this embodiment, all three modes are set by an external user command.In the Bluetooth-only or 802.11b-only mode, the device operates in thenative Bluetooth or 802.11b mode, respectively, i.e., whichever mode thedevice is in the other mode would be turned off. In the dualBluetooth-802.11b mode, Bluetooth and 802.11b baseband processors 204and 206, respectively, time-share the dual-mode radio front-end 202under the time-synchronous management of the dual-mode controller 200.

FIG. 12 describes the 802.11b network scan procedure for a new device tojoin an 802.11b network managed by a Point Controller (PC) device. Inthis case, the PC transmits a distinctive “beacon” every “CFP(ContentionFree Period)RepetitionInterval” that is bounded by “CFPMaximumDuration”parameter per IEEE 802.11b MAC specification. Unlike in an HomeRFnetwork, 802.11b transmissions take place at the same fixed carrierfrequency, i.e., no frequency hopping is allowed. The beacon containsspecific information about the existing 802.11b network.

A new device with an intention to join the 802.11b network performs anetwork scan procedure to search for a PC beacon. Search for the PCbeacon is repeated every “CFPMaximumDuration” interval per IEEE 820.11MAC specification at the same carrier frequency. If a PC beacon isreceived within the scanning window, the new device then extracts thenetwork identity information and the timing information from the beaconto join the 802.11b network.

For a dual-mode Bluetooth-802.11b communication device, the dual-modecontroller 200 manages the network access mechanism for both Bluetoothand 802.11b networks in a synchronous manner. A general illustration ofthe time interleaved access procedure is shown in FIG. 13.

The dual-mode controller 200 includes a synchronous state machine thatcombines the standby, inquiry scan, network scan, and connectionprocedures carried out by Bluetooth and 802.11b devices. It is importantthat dual-mode Bluetooth-802.11b devices interoperate with standardsbased Bluetooth-only or 802.11b-only devices. Network scan andconnection setup procedures for a dual-mode device should follow thesame rules as specified in the Bluetooth or 802.11b standards. In otherwords, dual-mode operation should not alter the synchronous time flow ofinterdependent states (idle, network scan, scan response, etc.) thataccomplish the respective network access procedures for Bluetooth or802.11b networks. Consequently, the objective of this inventiondisclosure is to devise a dual-mode controller such that Bluetooth and802.11b network access state machines are combined without individuallyaltering their functionalities. A description of one of the embodimentsof the dual-mode controller state machine is illustrated in FIG. 14.

The default state for the dual-mode controller is the standby mode 230.In the absence of any network connection, the dual-mode controllerinitiates a new network scan request 232 every “CFPMaximumDuration” per802.11b MAC specification. The very first network scan performed by thedual-mode controller searches for an 802.11b network. In this state, anew device performs a network scan procedure 236 searching for a 802.11bPC beacon. Total duration of the HomeRF network scan procedure is“CFPMaximumDuration”. If a TDMA beacon is received within the scanningwindow (block 238), the new unit extracts the network identityinformation and the timing information from the beacon to join the802.11b network. However, before the new device attempts to join the802.11b network based on the beacon information, the user is informedvia a display message etc. about the existence of the 802.11b networkand the types of services that are available. Accordingly, the user mayeither approve or disapprove joining the 802.11b network for thespecified services (block 240). If the user directs the dual-modecontroller to establish a connection with the 802.11b network, thedual-mode device then joins the 802.11b network and maintains connectionuntil the device transitions into an idle mode 244 or until the PCbeacon is no longer received by the unit 242. In both cases, the dualmode device goes into the dual-mode standby mode. If the user does notapprove connecting to the 802.11b network, the dual-mode controllerautomatically starts an inquiry scan procedure to search for theexistence of a Bluetooth network 248. As illustrated in FIG. 14, thedual-mode controller jumps to the same state, that is, starting aBluetooth inquiry scan if the initial 802.11b network scan fails to finda PC beacon. In this case, the Bluetooth inquiry scan procedure is runfor 10.24 seconds. This time duration is divided into four inquiry scanperiods of each 2.56 seconds. As shown in FIG. 13, the inquiry scanprocedure involves searching for a valid inquiry code for 11.25 msec(covering 16 inquiry frequencies) in a 2.56 second interval at a singlehop frequency. Same procedure is repeated at different hop frequenciesuntil an inquiry code is received but no more than 3 times. If a validBluetooth inquiry code is not received within the 10.24 second interval,the dual-mode device goes back to the dual-mode standby mode. In casethe unit receives a valid inquiry code 250, it goes into aninquiry-response mode 252 followed by the connection set up procedure254 with the master as described earlier in the text. Finally, if thereis no more data to be sent, the Bluetooth connection is terminated 256,and the dual-mode device goes back into the dual-mode standby mode.

While the embodiments described above generally have described portabledevices, the invention may be incorporated in non-portable devices. Forexample, a multi-mode controller may be implemented in a stationarydevice in an area where the wireless services may change over time.Typical scenarios may include where the quality of service or effectivedata rate of a given wireless service varies over time. In general, inmany applications wireless networking may be used in place ofnon-wireless connections. Hence, it should be understood that theteachings of the invention may be applied to virtually any connectivityapplication where there is a need to selectively utilize the services ofmore than one wireless network.

In summary, the invention described herein teaches improved techniquesfor managing and controlling network connectivity in wireless systems.While certain exemplary embodiments have been described in detail andshown in the accompanying drawings, it is to be understood that suchembodiments are merely illustrative of and not restrictive of the broadinvention. It will thus be recognized that various modifications may bemade to the illustrated and other embodiments of the invention describedabove, without departing from the broad inventive scope thereof. In viewof the above it will be understood that the invention is not limited tothe particular embodiments or arrangements disclosed, but is ratherintended to cover any changes, adaptations or modifications which arewithin the scope and spirit of the invention as defined by the appendedclaims.

1. A method for wireless communication, the method comprising: scanningby a wireless communication device, a plurality of radio frequencies forbeacon messages from a plurality of master communication devices, eachof said plurality of master communication devices associated with one ofa plurality of time-synchronous RF networks, to identify whetherestablishment of communication with at least one of said plurality oftime-synchronous RF networks is possible; selecting in accordance with apredefined criteria, a network associated with one of said beaconmessages, wherein said selected network is one of said plurality oftime-synchronous RF networks; and establishing communication with saidselected network by said wireless communication device.
 2. The methodaccording to claim 1, wherein said plurality of time-synchronous RFnetworks comprises a personal area network that supports data transferrates up to 1 Mbit/sec and a distance of up to 10 meters.
 3. The methodaccording to claim 1, wherein said plurality of time-synchronous RFnetworks comprises a Wireless Local Area (WLAN) network.
 4. The methodaccording to claim 1, comprising configuring said wireless communicationdevice to scan a first of said plurality of radio frequencies for afirst network during a first scanning window and scan a second of saidplurality of radio frequencies for a second network during a secondscanning window.
 5. The method according to claim 4, wherein said firstscanning window comprises a first predefined time period and said secondscanning window comprises a second predefined time period.
 6. The methodaccording to claim 5, wherein said first predefined time period is equalto said second predefined time period.
 7. The method according to claim5, comprising performing multiple scans during said first scanningwindow.
 8. The method according to claim 7, comprising performing eachof said multiple scans during said first scanning window for apredefined time period.
 9. The method according to claim 5, comprisingperforming multiple scans during said second scanning window.
 10. Themethod according to claim 9, comprising performing each of said multiplescans during said second scanning window for a predefined time period.11. The method according to claim 1, wherein said predefined criteriacomprises a user preference.
 12. The method according to claim 1,wherein said predefined criteria comprises relative bandwidth.
 13. Themethod according to claim 1, wherein said predefined criteria comprisesrelative quality of service (QoS).
 14. The method according to claim 1,wherein said predefined criteria comprises relative content.
 15. Themethod according to claim 1, comprising configuring said wirelesscommunication device to use a common portion of an RF radio front end tocommunicate with said plurality of time-synchronous RF networks.
 16. Themethod according to claim 1, comprising sequentially scanning saidplurality of radio frequencies for said beacon messages.
 17. The methodaccording to claim 1, comprising sequentially scanning said plurality ofradio frequencies for said beacon messages using different radiointerfaces.
 18. The method according to claim 1, comprising sequentiallyscanning said plurality of radio frequencies for said beacon messagesusing different protocols for at least a portion of said plurality oftime-synchronous RF networks.
 19. The method according to claim 1,comprising sequentially scanning said plurality of radio frequencies forsaid beacon messages using different frequency hopping and modulationrate parameters.
 20. The method according to claim 1, comprisingsequentially scanning said plurality of radio frequencies for saidbeacon messages using different baseband processors.
 21. The methodaccording to claim 20, wherein said different baseband processors use acommon RF radio front end to communicate with different ones of saidplurality of time-synchronous RF networks.
 22. The method according toclaim 1, comprising sequentially scanning for an inquiry sequence fromat least one of said plurality of time-synchronous RF networks.
 23. Asystem for wireless communication, the system comprising: at least onecircuit for use in a wireless communication device that enables scanningof a plurality of radio frequencies for beacon messages from a pluralityof master communication devices, each of said plurality of mastercommunication devices associated with one of a plurality oftime-synchronous RF networks, to identify whether establishment ofcommunication with at least one of said plurality of time-synchronous RFnetworks is possible; said at least one circuit enables selection of anetwork associated with one of said received beacon messages, inaccordance with a predefined criteria, wherein said selected network isone of said plurality of time-synchronous RF networks; and said at leastone circuit enables establishment of communication with said selectednetwork by said wireless communication device.
 24. The system accordingto claim 23, wherein said plurality of time-synchronous RF networkscomprises a personal area network that supports data transfer rates upto 1 Mbit/sec and a distance of up to 10 meters.
 25. The systemaccording to claim 23, wherein said plurality of time-synchronous RFnetworks comprises a Wireless Local Area (WLAN) network.
 26. The systemaccording to claim 23, wherein said at least one circuit enablesconfiguration of said wireless communication device to scan a first ofsaid plurality of radio frequencies for a first network during a firstscanning window and scan a second of said plurality of radio frequenciesfor a second network during a second scanning window.
 27. The systemaccording to claim 26, wherein said first scanning window comprises afirst predefined time period and said second scanning window comprises asecond predefined time period.
 28. The system according to claim 27,wherein said first predefined time period is equal to said secondpredefined time period.
 29. The system according to claim 27, whereinsaid at least one circuit performs multiple scans during said firstscanning window.
 30. The system according to claim 29, wherein said atleast one circuit performs each of said multiple scans during said firstscanning window for a predefined time period.
 31. The system accordingto claim 27, wherein said at least one circuit performs multiple scansduring said second scanning window.
 32. The system according to claim31, wherein said at least one circuit performs each of said multiplescans during said second scanning window for a predefined time period.33. The system according to claim 23, wherein said predefined criteriacomprises a user preference.
 34. The system according to claim 23,wherein said predefined criteria comprises relative bandwidth.
 35. Thesystem according to claim 23, wherein said predefined criteria comprisesrelative quality of service (QoS).
 36. The system according to claim 23,wherein said predefined criteria comprises relative content.
 37. Thesystem according to claim 23, wherein said at least one circuit enablesconfiguration of said wireless communication device to use a commonportion of an RF radio front end to communicate with said plurality oftime-synchronous RF networks.
 38. The system according to claim 23, saidat least one circuit enables sequential scanning of said plurality ofradio frequencies for said beacon messages.
 39. The system according toclaim 23, wherein said at least one circuit enables sequential scanningof said plurality of radio frequencies for said beacon messages usingdifferent radio interfaces.
 40. The system according to claim 23,wherein said at least one circuit enables sequential scanning of saidplurality of radio frequencies for said beacon messages using differentprotocols for at least a portion of said plurality of time-synchronousRF networks.
 41. The system according to claim 23, wherein said at leastone circuit enables sequential scanning of said plurality of radiofrequencies for said beacon messages using different frequency hoppingand modulation rate parameters.
 42. The system according to claim 23,wherein said at least one circuit enables sequential scanning of saidplurality of radio frequencies for said beacon messages using differentbaseband processors.
 43. The system according to claim 42, wherein saiddifferent baseband processors use a common RF radio front end tocommunicate with different ones of said plurality of time-synchronous RFnetworks.
 44. The system according to claim 23, wherein said at leastone circuit enables sequential scanning for an inquiry sequence from atleast one of said plurality of time-synchronous RF networks.